The invention concerns a pressure regulating valve for regulating pressure in a high-pressure fuel accumulator for an internal combustion engine.
Such a pressure regulating valve is known for example from publication DE 10 2004 002 964 A1. It comprises a closing member held in a valve chamber and actuatable via a magnetic actuator, which member closes or opens a connection from the high-pressure accumulator into a low-pressure line. Furthermore the valve comprises a spring element arranged such that on stoppage of the internal combustion engine, the connection from the high-pressure accumulator to the low-pressure line is opened. The spring element is firstly supported on an armature plate and secondly on a radial shoulder of a stepped bore formed in a valve housing, which furthermore holds a valve piston connected to the armature plate. When the magnetic actuator is powered, the armature plate and the valve piston are moved in the direction of a valve seat against the spring force of the spring element, wherein the valve piston presses the closing member into the valve seat. In this switch position, the connection of the high-pressure accumulator to the low-pressure line is closed. When the power supply to the magnetic actuator is interrupted, the armature plate and the valve piston are reset via the spring force of the spring element, lifting the closing member away from the valve seat and opening the valve. In this switch position, the connection of the high-pressure accumulator to the low-pressure line is open, wherein fuel flowing out of the high-pressure accumulator via the low-pressure line is supplied to a fuel storage container.
Pressure fluctuations can be transmitted to the pressure regulating valve via the low-pressure line and a low-pressure system connected thereto, which normally comprises a fuel storage container, a pre-delivery pump and the supply region of a high-pressure pump. As a result of these pressure fluctuations, the valve piston of the pressure regulating valve can execute uncontrollable movements and the pressure regulating valve may open unintentionally. This should be avoided since the pressure fall in the high-pressure accumulator, which is caused on opening of the pressure regulating valve, can lead to instabilities and in some cases the pressure can fall below the minimum pressure necessary to start the engine. Furthermore the pressure regulating valve can be excited to natural vibrations via the low-pressure region, which leads to undesirable pressure peaks in the low-pressure system and/or to unpleasant noise development.